AU MIDI Effect Plugins
Note: AU Plugins are supported in the Mac version only. If a song with an AU plugin is opened with MultitrackStudio for Windows a Missing MIDI Effect placeholder will appear.An AU MIDI Effect is a AU Plugin that can process MIDI messages. You can select an AU MIDI Effect by clicking the MIDI effect slot's down arrow. The AU MIDI Effect plugins appear in the list's Plugins section.
Note: the 'Apply to track' option relies on plugins being able to save and restore settings, so it won't work with demo versions that can't do this.
MIDI 2.0 / MPE
Starting with macOS 12 AU plugins that support the MIDI 2.0 protocol will receive MIDI 2.0. AU MIDI effects do not receive per-note controls otherwise.
MIDI output from plugins is converted from MPE to MIDI 2.0. You can avoid this by setting the per-note pitchbend range to zero (in this case MPE to MIDI 2.0 conversion will only take place if the plugin sends MPE configuration messages (RPN 6)).